复掺石灰石粉与粉煤灰对水泥砂浆性能的影响

Effect of Compounding Limestone Powder and Fly Ash on Properties of Cement Mortars

将石灰石粉与粉煤灰复掺,以不同质量分数(0、10%、20%和30%)取代水泥,制备水泥砂浆,对其力学与吸水性能进行研究,同时分析砂浆的微观结构。结果表明,复掺石灰石粉与粉煤灰降低了水泥砂浆在各龄期的力学性能,且降低程度随着复掺量的增加而增大。养护7 d时,砂浆吸水性能随石灰石粉与粉煤灰复掺量的增加而提高;养护28 d时,复掺少量石灰石粉与粉煤灰(10%或20%)降低了砂浆吸水性能;但复掺量较高(30%)时,砂浆吸水性能高于纯水泥砂浆。复掺石灰石粉与粉煤灰使胶凝体系的水化产物数量减少,砂浆内有效水灰比增大,水分蒸发后形成的孔体积更大;但复掺组砂浆的曲折度均大于纯水泥砂浆。

The limestone powder and fly ash were co-mixed to replace cement at different mass fractions(0,10%,20%and 30%),and the cement mortars were then prepared.The mechanical and water absorption properties of mortars were studied,and their microstructure was analyzed.The results show that the mechanical properties of cement mortars at various ages are reduced by the co-addition of limestone powder and fly ash,and the reduction degree increases with an increase of the co-addition amount.At 7 days of curing,the water absorption performance of mortar is improved with an increase of the co-addition amount of limestone powder and fly ash.At 28 days of curing,adding a small amount of limestone powder and fly ash(such as 10%or 20%)reduces the water absorption performance of mortar;however,the water absorption performance of mortar with the greater co-addition amount(such as 30%)is still higher than that of the pure cement mortar.The co-addition of limestone powder and fly ash reduces the amount of hydration products in the cementitious system.Meanwhile,the effective water-cement ratio within the mortar is increased,and thereby the pore volume is increased after the evaporation of water.However,the tortuosity of co-mixed mortar is greater than that of pure cement mortar.